The present invention relates generally to exercise apparatus and particularly to exercise apparatus wherein a bicycle-type frame supports a seated operator or user who pedals in a manner generally similar to the pedaling of a conventional bicycle. In such conventional apparatus, the crank arms, like those of a conventional bicycle, extend in opposite directions from a common geometric axis and are fixed to a sprocket rotatable about the same axis. The sprocket is often or typically coupled by a chain drive to a wheel positioned in front of the operator, and the wheel is provided with a snubbing apparatus which is adjustable to selectively vary the degree of resistance to movement.
Such conventional exercise apparatus is limited in the exercise benefits attained, because of the geometric relationship between the pedal crank arms. It has been found that substantial exercise benefits may be achieved by changing the angular relationship between the crank arms. It has been found that, if the crank arms which support the respective pedals are disposed so that they extend in exactly the same angular direction from a single geometric axis substantial benefits are achieved in terms of attaining exercise which would not otherwise be possible. For convenience in describing this geometic relationship the term "side by side" will be used to characterize the relationship of the crank arms when they extend in a single direction from their geometric axis. With the side by side relationship of the crank arms, the legs of the user move synchronously as the respective pedals are moved through their 360 degree travel.
The prior art includes the apparatus described in U.S. Pat. No. 3,485,495. That U.S. patent shows crank arms which are disposed in side by side relationship rather than the opposed relationship common to conventional bicycle type exercisers. Changing the relative positions of the crank arms in the apparatus of this patent involves difficulty, work and inconvenience, so that it has not had wide adoption.
It is an object of the invention to provide bicycle-type exercise apparatus in which the respective pedal crank arms may be easily indexed relative to each other to position the crank arms either in side by side relationship or opposed relationship.
It is another object of the invention to provide such apparatus which allows the user to selectively index the respective crank arms without tools and while seated on the apparatus.